I cannot find anything about her, but the caption shows she was the daughter of Alexandrina Laval.
From Wikimedia.
The Baroness is dressed in ca. 1830 style with a pleated bodice, dual upper puffed sleeves, and a full skirt.
Keywords: Zinaida Trubetskoy, Zinaida Lebtseltern, Baroness de Kars, Laval family, Trubetskoy family, Baroness, curly coiffure, knotted bun, off shoulder straight neckline, pleated bodice, dual upper puffed sleeves, cuffs, waist band, bows, natural waistline, full skirt, necklace, earrings